Finally, we evaluated whether particular clinical or hemodynamic parameters influenced amikacin PK and propose new recommendations for the loading dose of amikacin in this critically ill population.Materials besides and methodsStudy design, patients, and antibiotic treatmentThis was an open, prospective, multicenter, noncomparative study performed in four polyvalent ICUs from four Belgian hospitals between January 2005 and June 2006. The study protocol was approved by the Ethics Committees of the different hospitals. Written informed consent was obtained from each patient or his or her legal guardian. Patients with a diagnosis of severe sepsis or septic shock according to standard criteria [19], in whom amikacin treatment was indicated, were consecutively enrolled in the study.

The aminoglycoside was given in combination with a broad-spectrum ��-lactam (ceftazidime, cefepime, piperacillin-tazobactam, or meropenem), according to local clinical practice. Exclusion criteria were younger than 18 years of age, pregnancy, burns or cystic fibrosis (because of increased Vd), neuromuscular disease, body mass index (BMI) >40 kg/m2, chronic renal failure requiring dialysis, amikacin treatment in the previous 2 weeks, and known allergy to aminoglycosides. No patient was included more than once. The study period was limited to the first 24 hours of treatment.All patients included in the study received a loading dose of 25 mg/kg of amikacin based on TBW; this regimen was defined for an expected mean Vd of 0.4 L/kg and a target peak of 64 ��g/ml [17,20,21]. Doses were rounded off at multiples of 125 mg.

The drug was administered over a 30-min period by using an infusion pump, and the tubing was flushed with 0.9% sodium Entinostat chloride after the dose was administered. Blood samples for drug assays were taken immediately before administration (0 h) and 1 h, 1 h 30, 4 h 30, 8 h, and 24 h thereafter. These blood-sampling time points are supposed to belong to the elimination phase of the drug. The exact time of sampling was recorded. Blood was collected in a 5-ml plain tube (without anticoagulant). When a clot had completely formed (15 to 30 min), the sample was centrifuged at 4��C, and the serum was stored at – 80��C until analysis.Analytic method for amikacinAmikacin concentrations were quantified at the end of the study in a central reference laboratory (St-Luc Hospital) by using a validated fluorescence polarization immunoassay with the TDx analyzer (Abbott Laboratories, Abbott Park, IL, USA). Routine daily quality controls (5, 15, and 30 ��g/ml) and calibrators (3, 10, 20, 35, and 50 ��g/ml) were provided by Abbott Laboratories. No sample preparation was required for the assay. According to the manufacturer, the limit of quantification (LOQ) is 0.8 ��g/ml.